Discussion on Quick Estimation Method of Non-standard Pressure Vessel Quotation

Discussion on Quick Estimation Method of Non-standard Pressure Vessel Quotation

According to the non-standard pressure vessel manufacturer’s own manufacturing equipment and technical capabilities, combined with examples to explore the rapid estimation method of non-standard pressure vessel production prices, the method can be widely used in the production of non-standard pressure vessels to quickly and accurately determine the price of competitive bidding, as well as reasonable control of the production process costs.

What is a non-standard pressure vessel?

Non-standard pressure vessel mainly refers to the industrial production for a specific application area, with a specific process function of the variable, not a series, for the gas or liquid to complete the reaction, heat transfer, separation, storage and other production processes, and has a specific function of bearing a certain pressure of the closed equipment. Non-standard pressure vessel is an important equipment in the petrochemical industry, with complex operation, high safety, large volume, wide range of applications and other characteristics. In the petrochemical project to determine the process line and process package, the design unit according to the specific function of the pressure vessel in the project, drawing construction drawings, and then by the non-standard pressure vessel manufacturing plant according to the requirements of the design drawings, processing and production of non-standard pressure vessel entity, delivered to the project site, to achieve the overall function of the project.
At present, the main way to obtain orders for non-standard pressure vessel manufacturing plant is through the owner, the engineering company or its commissioned bidding unit to organize public bidding, that is, after the expert bid evaluation committee, the supply manufacturers’ qualifications, performance, technology, equipment and other aspects of capacity and non-standard pressure vessel bid price comprehensive evaluation to determine the winning manufacturer. Due to the rapid development of the equipment manufacturing industry, the main domestic non-standard pressure vessel manufacturers have been upgraded and enhanced in recent years in terms of manufacturing capacity, and the gap between them is gradually narrowing. In this case, how to quickly and accurately estimate the price of equipment bids to become one of the most critical factors in winning the bid. The following is a petrochemical plant a tower equipment as an example, from its production cost point of view to discuss the manufacturer of non-standard pressure vessel equipment bidding price of rapid measurement method.

1. Technical preparation

In the non-standard pressure vessel production price estimates, must be fully prepared for the relevant technology. First of all, we must check the technical parameters of non-standard pressure vessels and the corresponding manufacturing requirements, and accordingly develop the overall manufacturing program of pressure vessels and key manufacturing control processes.

1.1 Verification of technical parameters

According to the non-standard pressure vessel design and manufacturing drawings, verify the category of non-standard pressure vessels, design pressure and temperature, specification weight, internal structure and other technical parameters, to lay a good foundation for rapid and accurate estimates.
Such as a tower of the relevant technical parameters are as follows:

• (1) Category for Ⅲ container;
• (2) Design pressure 1.88MPa / FV, design temperature 360/336 ℃;
• (3) The specification is Φ9800/10600/11800×131600×86/98/118/132mm;
• (4) Welded inner part has 195 layers of tower plate;
• (5) Material Q345R(N);
• (6) Total net weight of 4350t, of which 3549t straight cylindrical shell weight, head, conical transition section weight 313t, flange forgings, receiver manhole and other finished parts 71t, welded internal parts 261t, skirt base ring, positioning template, sample plate, reinforcement ring, insulation support ring, lugs, pre-welded gasket, support ears, etc. 156t.

1.2 Develop overall manufacturing plan

According to the characteristics, technical parameters and manufacturing requirements of the non-standard pressure vessel, the overall manufacturing plan is formulated to provide the necessary conditions for the determination of the subsequent price estimation data (such as the utilization rate of plates, the consumption of welding materials per ton of non-standard pressure vessel production, the number of man-days of labor input, etc.). As mentioned above, the main manufacturing scheme of the tower is as follows:
1.2.1 Assembly welding

The non-standard pressure vessel has a large diameter, wall thickness, extra heavy, a single cylinder section weight and other characteristics, to be all in the plant under the vertical state to complete the segmented cylinder welding, all the receiver and the tower body directly welded inside and outside the installation of welding work; head, cone using melon flap pressed into shape after the steel platform to complete the overall group welding work.

1.2.2 Welding process
In the welding process to promote efficient and advanced technology, welding work is mainly automatic welding (the longitudinal seam of the cylinder adopts submerged arc automatic welding SAW, the ring seam adopts narrow gap MAGW automatic welding), supplemented by semi-automatic welding, eliminating the inefficient welding rod welding.
1.2.3 Non-destructive testing
Equipment shell A, B class welds 100% TOFD, level II qualified, 100% UT, level I qualified, 100% MT, level I qualified, D class welds DN ≥ 200: 100% UT, level I qualified, DN<200: 100% MT, level I qualified, 100% RT, level II qualified for the receiver and flange ring seam.
1.2.4 Heat treatment, hydraulic test, etc.
The whole heat treatment of the tower equipment in the furnace, the equipment in the water pressure test, the outer surface of the factory before the sandblasting anti-corrosion, nitrogen-filled packaging work.
1.2.5 Work period and labor
The tower in-plant manufacturing period of 13 months, need to invest in labor 135 people.
2 non-standard pressure vessel ex-factory price composition and its calculation method
The ex-factory price of non-standard pressure vessel is composed of production cost, profit and tax, of which, the production cost is composed of the main material purchase cost, auxiliary consumption material purchase cost and processing fee.

2.1 Main material procurement cost

The procurement cost of main material refers to the procurement cost (excluding tax) of non-standard pressure vessel body (including cylinder, head, conical transition section and other shells, inner parts and various parts of steel plates, and accessories such as receiver manhole and flange forgings), including the procurement cost of steel plates and accessories such as receiver manhole and flange forgings (finished parts).
2.1.1 Steel plate procurement cost
Steel plate procurement cost = metal shell (or inner parts, components) net weight ÷ plate utilization rate × steel plate procurement unit price excluding tax
The plate utilization rate of non-standard pressure vessel body steel plate varies according to the structure form of non-standard pressure vessel body, such as the plate utilization rate of straight shell is generally between 95% and 98%, the plate utilization rate of head and cone transition section is between 55% and 65%, the plate utilization rate of welded inner parts material is about 80%, other (such as saddle, skirt seat bottom ring plate, positioning template, reinforcement ring, insulation support ring, lugs, pre-welded gaskets, lugs, etc.) according to manufacturing experience, the utilization rate of the integrated plate is about 75%.
2.1.2 Procurement cost of finished parts
Finished parts procurement cost = net weight of finished parts ÷ plate utilization rate × unit price of finished parts procurement without tax
The net weight of finished parts such as pipe manhole and flange forgings is calculated according to the orifices listed in the design and manufacturing drawings.

2.2 Procurement cost of auxiliary consumable materials

Auxiliary consumable material procurement cost, refers to the non-standard pressure vessel processing production required welding materials (welding wire, welding rod, etc.), “three gas (refers to oxygen, argon, acetylene gas and other gases), tooling, means of materials, and according to the requirements of the factory for non-standard pressure vessel external surface corrosion required sand blasting (shot) of sand or steel shot, paint and other procurement costs (excluding tax).
2.2.1 Welding material cost
Non-standard pressure vessel production, welding material costs account for a large proportion of the above auxiliary consumption of material costs. According to the non-standard pressure vessel manufacturing welding process and non-standard pressure vessel manufacturer’s historical experience statistics, welding material use can be calculated according to a percentage of the net weight of the non-standard pressure vessel body, other auxiliary consumable material costs are estimated according to a percentage of the cost of the main material.
Welding material cost = net weight of equipment body (tons) × welding material consumption per ton of non-standard pressure vessel production × welding material purchase unit price excluding tax
2.2.2 Other auxiliary consumable material cost
Other auxiliary consumable material cost = main material purchase cost × other auxiliary consumable material cost coefficient
Wherein, the cost of other auxiliary consumable materials is calculated according to the design requirements and historical experience data.

2.3 Processing cost

Processing cost is usually composed of labor cost, machinery cost, outsourcing (outsourcing) processing cost, inspection and testing cost, etc.
2.3.1 Labor cost
Labor cost = number of man-days input × unit price of man-days
Among them, the number of man-days can be calculated according to the manufacturing duration and labor input plan in the non-standard pressure vessel manufacturing program, and the unit price of man-days is determined according to the manufacturing plant’s own labor cost measurement.
2.3.2 Machinery cost
Machinery costs include all kinds of equipment used in the manufacture of non-standard pressure vessels, depreciation of machinery and its power, lubricants and other consumption, according to the experience of non-standard pressure vessel manufacturing plant data according to a percentage of the main material purchase cost.
Machinery cost = main material purchase cost × machinery cost coefficient
2.3.3 Inspection and testing fees
Inspection and test fee = non-standard pressure vessel net weight × inspection and test fee excluding tax ton unit price
Among them, the unit price of inspection and test fee per ton can be combined with the inspection requirements of non-standard pressure vessel manufacturing according to historical experience data statistics and dynamic adjustment.
2.3.4 Outsourcing processing fees
Usually, the non-standard pressure vessel manufacturing plant due to the limitations of its manufacturing equipment and processing capacity will be the head, extra-thick conical shell transition section, equipment parts, etc. completely entrusted to other manufacturers for processing or press molding, resulting in outsourcing, outsourcing processing costs.
Outsourcing (outsourcing) processing cost = net weight of outsourced (outsourcing) processing parts × unit price of processing and production without tax
2.4 Profit
Profit = production cost × profit margin
Usually, the industry profit margin of non-standard pressure vessel manufacturing is between 10% and 15% of the production cost, the manufacturer can be determined according to their own bidding strategy.
2.5 Taxes
Tax = (production cost + profit) × VAT rate
According to the national tax law, the applicable VAT rate of manufacturing industry is 16%.

3. A tower quotation quick estimate example

According to the aforementioned technical parameters of a tower, manufacturing requirements and manufacturing solutions, and after the purchase of quotation, determine the relevant cost data for the production of the equipment is:

• (1) Plate procurement cost: As the tower has both the shape and size of the super large tower, but also has the thickness of the reactor steel plate, therefore, the body of the steel plate used in addition to the requirements of GB713-2008 standards, but also must meet the steel plate by heat treatment Zhang for simulation of heat treatment state of the tensile test, impact test and other test requirements and inspection requirements. Now the body plate using the price of Maeyang steel mill, the average purchase price of 6140 yuan / t, excluding tax unit price of 5293 yuan / t.
• (2) Plate utilization rate: according to the manufacturing process of the manufacturer, the plate utilization rate of the straight shell and shaped shell is 98% and 65% respectively, the plate utilization rate of the welded inner parts is 80%, and the comprehensive plate utilization rate of other accessories is 75%.
• (3) Flange forgings, receiver manhole and its accessories (finished parts): market purchase price 25530 yuan / t, excluding tax price 22009 yuan / t.
• (4) Per ton of tower production welding material consumption is calculated at 3.6%, welding material market purchase price 8500 yuan / t, excluding tax price 7328 yuan / t; other auxiliary consumption material cost factor of 23%.
• (5) The unit price of labor days is 390 yuan/d, and the working time is considered as 30 days/month.
• (6) According to the empirical data of production cost, the coefficient of machinery cost is calculated by 39%.
• (7) The unit price of inspection and test fee without tax is calculated as 535 yuan/t.
• (8) Head and conical transition section are pressed by professional head manufacturer, calculated at market processing price (excluding tax) of RMB 1481230; welding inner parts are processed by outsourced tower inner parts factory, including tax price of RMB 4500/t, excluding tax price of RMB 3879/t.

According to the aforementioned method and related data calculated by a tower equipment factory price as shown in Table 1.

4. Conclusion

Table.1 a tower equipment factory bid price valuation table

Number	Expense name	Cost calculation formula	Total price (yuan)	Note
一	Production cost		68,795, 997
1	Main material purchase cost		26, 107, 428	VAT deductible, not included
(1)	Shell steel plate		21, 717, 004
①	Straight cylindrical shell steel plate	3549″ 98% x 5293 yuan/t	19, 168, 221
②	Special-shaped shell steel plate	313″ 65% x 5293 yuan/t	2, 548, 783	Including: head, conical transition section
(2)	Finished parts	71tx 22009 yuan/t	1, 562, 639	Including: flange forgings, connecting pipe manhole and other accessories
(3)	Welded internals	261″ 80% x 5293 yuan/t	1726841
(4)	Other parts	156″ 75% x 5293 yuan/t	1,100, 944	Including: skirt bottom ring, positioning template, template, reinforcement ring, insulation support ring, lifting lug, pre-weldment base plate, support lug, etc
2	Purchase cost of auxiliary consumable materials		7, 152, 273	VAT deductible, not included
(1)	Welding material	4350tx 3.6% x 7328 yuan/t	1,147, 565	Including: welding wire, welding rod
(2)	Other consumable materials	Main material procurement cost x 23%	6, 004, 708	Including: paint, three gases (oxygen, argon, acetylene, etc.), tooling costs, means and materials, etc
3	Process cost		35, 536, 296
(1)	Labor cost	135 people x 13 months x 30 days x 390 yuan/workday	20, 533, 500
(2)	Machinery cost	Main material procurement cost x 39%	10, 181, 897
(3)	Inspection and test fee	4350t 535 yuan/t	2, 327, 250	Price excluding tax
(4)	Head and cone section pressing cost		1481230	Price excluding tax
(5)	Entrusted processing of welded internals	261t x 3879 yuan/t	1012419	Price excluding tax
二	Profit	㈠ x 12%	8,255, 520	Calculated by 12% of production cost
三	Taxes	(一 + 二) 16%	12328243	VAT rate is 16%
四	Total ex-factory price		89, 379, 760

Non-standard pressure vessel manufacturer according to its own manufacturing equipment and technical capabilities, through the analysis, collation of different structural forms, different materials, different design pressure of non-standard pressure vessel historical production cost data, the above introduced non-standard pressure vessel factory price rapid estimation method of various types of coefficients, plate utilization rate and related to some comprehensive ton unit price to be accumulated, not only can quickly and accurately estimate the non-standard Pressure vessel ex-factory price, and can truly reflect the actual manufacturing process of non-standard pressure vessels in the various costs and expenses, for the manufacturing plant to quickly and accurately determine the non-standard pressure vessel bid price and reasonable control of production costs to provide a reliable basis for enterprises to improve economic efficiency has a very important significance.

Source: China Pressure Vessels Manufacturer – www.secmachinery.com